Analyses of high-throughput human data, including gene expression profiles of human brains, constitute a powerful strategy for nominating biological networks associated with Alzheimer?s disease (AD) pathophysiology as potential therapeutic targets. The Accelerating Medicines Partnership-Alzheimer?s Disease (AMP-AD) Target Discovery Project has defined consensus, AD-associated molecular networks based on joint analyses of transcriptomic profiles in ~2,000 human brain autopsy samples. The critical next step is to rigorously test computational predictions in experimental animal models to (i) unambiguously link promising networks to specific AD triggers (i.e. Amyloid-, Tau, and/or aging), (ii) confirm the network architecture, (iii) validate implicated molecular pathways in the nervous system context, and (iv) discover which molecular changes are truly causal, including distinguishing between amplifiers of pathogenesis versus protective, compensatory responses. We have developed a cross-species strategy for functional dissection of emerging AD molecular networks using high-throughput assays in the nervous system of transgenic Drosophila expressing human wild-type human Tau or the Amyloid- peptide. When applied to candidates from AD-associated networks, these rapid and complementary in vivo assays enable identification of those genes and pathways that are likely causal modifiers of Tau- and/or A-induced neuronal dysfunction, including both drivers of pathogenesis and compensatory responses. The overall goal of this proposal is to deploy our cross-species strategy to accelerate the discovery, refinement, and functional dissection of AD molecular networks derived from human brain transcriptomes and proteomes. First (AIM 1), transcriptomic and proteomic profiling in Drosophila AD models will be coupled with comprehensive screening of conserved network candidates in order to identify those genes causally linked to neurodegeneration and differentiate in vivo interactions with Tau-, A-, or other age-dependent mechanisms. The proposed screen will deploy robotic instrumentation for high-throughput, quantitative analyses of Drosophila motor impairment due to neuronal dysfunction. Second (AIM 2), using systems biology approaches, gene expression and functional data from Drosophila will be integrated with the human AD networks. The resulting multi-scale atlas of AD molecular systems will pinpoint causal networks and key gene/protein drivers with the greatest potential to alter neurodegeneration upon perturbation. Next (AIM 3), we will experimentally confirm the network architecture for the most promising modules highlighting key drivers with roles as AD amplifying/protective factors. Lastly (AIM 4), all project results will be made publicly available via the AMP-AD Knowledge Portal. IMPACT: Our integrative, cross-species discovery strategy will comprehensively probe AD molecular networks with powerful, in vivo functional assays to reveal age- dependent drivers, including amplifiers and protectors, for Tau- and A-induced neurotoxicity, and elucidate the complex network architecture underlying AD pathogenesis.